A cactus is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1,750 known species of the order Caryophyllales. The word cactus derives, through Latin, from the Ancient Greek word κάκτος (káktos), a name originally used by Theophrastus for a spiny plant whose identity is now not certain. Cacti occur in a wide range of shapes and sizes. They are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the north, with the exception of Rhipsalis baccifera, which is also found in Africa and Sri Lanka. Cacti are adapted to live in very dry environments, including the Atacama Desert, one of the driest places on Earth. Because of this, cacti show many adaptations to conserve water. For example, almost all cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Unlike many other succulents, the stem is the only part of most cacti where this vital process takes place. Most species of cacti have lost true leaves, retaining only spines, which are highly modified leaves. As well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of true leaves, cacti's enlarged stems carry out photosynthesis.
Pachypodium is a genus of succulent spine-bearing trees and shrubs, native to Madagascar and Africa. It belongs to the family Apocynaceae.
Echinocereus engelmannii, the strawberry hedgehog cactus or Engelmann's hedgehog cactus, is a cactus commonly found in desert areas of the southwestern United States and the adjacent areas of Mexico, including the states of California, Nevada, Utah, Arizona, Baja California and Sonora.
Echinocereus reichenbachii is a perennial plant and shrub in the cactus family. The species is native to the Chihuahuan Desert and parts of northern Mexico and the southern United States, where they grow at elevations up to 1,500 meters (4,900 ft). This cactus earned the Royal Horticultural Society's Award of Garden Merit.
Opuntia humifusa, commonly known as the devil's-tongue, eastern prickly pear or Indian fig, is a cactus of the genus Opuntia present in parts of the eastern United States and northeastern Mexico.
Acanthocereus tetragonus is a species of cactus that is native to Florida and the Lower Rio Grande Valley of Texas in the United States, Mexico, Central America, the Caribbean, and northern South America. The species is invasive in New Caledonia. Common names include night-blooming cereus, barbed-wire cactus, sword-pear, dildo cactus, triangle cactus, and Órgano-alado de pitaya (Spanish). The miniature cultivar is known as fairy castle cactus. It was originally described by Carl Linnaeus in 1753 as Cactus tetragonus but was moved to the genus Acanthocereus in 1938 by Pieter Wagenaar Hummelinck.
Harrisia fragrans is a rare species of cactus known by the common name fragrant prickly apple. It is endemic to Florida, where it is known only from St. Lucie County. The plant's habitat has been almost completely consumed by development, leading to its rarity. It is a federally listed endangered species of the United States.
Moraea aristata is a species of flowering plant in the family Iridaceae. It is referred to by the common names blue-eyed uintjie or Blouooguintjie in Afrikaans.It is endemic to the city of Cape Town and is considered to be critically endangered.
Pelecyphora sneedii is a rare species of cactus known by the common names Sneed's pincushion cactus and carpet foxtail cactus. It is endemic to the Chihuahuan Desert of the southwestern United States and northwestern Mexico. It is a small, variable cactus with a lengthy taxonomic history, and is often subdivided into a number of subspecies or varieties. It is usually found on steep, rocky habitats, primarily of limestone geology, in desert scrub or coniferous forest. A species of conservation concern, P. sneedii faces threats from poaching, urban encroachment, and wildfires.
Echinocereus viridiflorus is a species of cactus known by the common names nylon hedgehog cactus, green pitaya, and small-flowered hedgehog cactus. It is native to the central and south-central United States and northern Mexico, where it can be found in varied habitat types, including desert scrub, woodlands, dry grasslands, and short-grass prairie.
Pediocactus sileri is a rare species of cactus known by the common names Siler's pincushion cactus and gypsum cactus. It is native to southwestern Utah and northwestern Arizona in the United States. It is limited to a specific type of soil, individuals are often spaced far apart, and the species is threatened by a number of human activities such as off-road vehicle use, poaching, and uranium mining. This is a federally listed threatened species of the United States.
Pediocactus bradyi subsp. despainii is a rare species of cactus known by the common names Despain's cactus and San Rafael cactus.
Pediocactus knowltonii is a rare species of cactus known by the common names Knowlton's miniature cactus, Knowlton's pincushion cactus, and Knowlton's minute cactus.
Sclerocactus brevispinus is a rare species of cactus known by the common name Pariette cactus. It is endemic to Utah in the United States, where it is known only from the Pariette Draw, a draw in Duchesne County. It is threatened by a number of processes and human activities.
Sclerocactus wetlandicus is a rare species of cactus known by the common name Uinta Basin hookless cactus. It is endemic to Utah in the United States, where it is known only from the Uinta Basin. It may also be called the Pariette cactus, but this name is more appropriate for Sclerocactus brevispinus, the species endemic to the Pariette Draw of Duchesne County.
Consolea corallicola is a species of cactus known by the common names Florida semaphore cactus and semaphore pricklypear. It is endemic to Florida in the United States, where it is limited to the Florida Keys.
Cochemiea thornberi is a species of cactus known by the common names Thornber's fishhook cactus and Thornber's nipple cactus. It is native to Arizona in the United States and Sonora in Mexico.
Sclerocactus sileri, the Siler fishhook cactus, is a rare and very small cactus found mostly in mineral-rich desert areas of intermediate elevations, notably in the American states of Utah, Nevada, and northern Arizona.
Peniocereus striatus is a species of cactus known by several common names, including gearstem cactus, cardoncillo, jacamatraca, sacamatraca, and dahlia-rooted cactus. It is endemic to the Sonoran Desert, where it occurs in Baja California, Sinaloa, and Sonora in Mexico and Arizona in the United States.
Pediocactus simpsonii, known by the common names mountain cactus, snowball cactus, and mountain ball cactus, is a relatively common cactus that has adapted to survive in cold and dry environments in high elevation areas of the western United States. It can be found at higher elevations than any other cactus in North America. While not a landscape dominating plant, it is a relatively common species and the most common member of the genus Pediocactus. Because of its beauty and adaptation to cold environments it is sometimes grown by gardeners in areas that have few other choices due to the limited number of cactuses with cold adaptations. Like many cactuses its populations are sometimes threatened by this desirability due to the theft or removal of plants from the wild by collectors.
